Inspecting sealed containers in closed cartons



INSPECTING SEALED CONTAINERS IN CLOSED CARTONS l med Aug. 21. 1967' Jue24, 1969 E. M. MURLEY, JR

Sheet INVENTOR. ELLSWORTH I\,|\urLEv Je. WQ: ww

June 24, 1969 l E. M. MURLEY, JR 3,451,546

INSPECTING SEALED CONTAINERS IN CLOSED CARTONS Filed Aug. 21, 1967 sheetZ of 2 s REJECT D INVENTOR. Mmm mmowk,

Ammev United States Patent O U.S. Cl. 209-73 9 Claims ABSTRACT OF THEDISCLOSURE The inspection of sealed containers, particularly glasscontainers, having metal caps which incorporate a flippanel that assumesa concave configuration when the container is under sufficient vacu-umand a convex configuration when the vacuum is unsatisfactory, is carriedout after the containers are packed within a carton by using microwaveradiation and reflection technique. A klystron operated in themillimeter wave band at low power is coupled to feed horns and by theuse of dielectric lenses the millimeter waves, which penetrate thecartons, are drected toward and reflected from the containerflip-panels. The reflected waves are picked -up by horns coupled tbolometers. The pickup horns are positioned behind masks so thatdivergent reected waves will reach the horns while convergentreflections will be intercepted by the mask, thus the output of thebolometer serves as an indication of the vacuum condition of thecontainers.

Background of the invention Present-day packers of food products, suchas baby foods, where the containers used are glass; normally seal thecontainers with a metallic closure. Even duringvthe filling of thecontainers, the prod-uct may be relatively warm and after the containersare'lled and the closures sealed thereon, the containers are frequentlyplaced in retorts for the purpose of heating the container contents toabove the pasteurization temperature, so as to be sure that no bacteriaremains in the food product. Even in those situations wherepasteurization is not necessary, the containers are usually filled witha hot product and steam is used to expel air as the closure is sealedonto the conrainer. Cooling down of the container will produce a degreeof vacuum within the containerwhich results in depressing the flip-panelnormally associated with this type of closure. The containers areusually inspected after they are sealed to determine if the properdegree of vacuum is present'within the container by examining theflip-panel of the container optically with a system such as thatdisclosedin United States Patent No. 3,131,815 issued May 5, 1964, andassigned to the assignee of this application. After the containers arefilled, sealed and inspected, they are placed in cartons and the cartonflaps are glued or otherwise closed and the product is ready to beshipped to the market or wholesalers, as the case may be.

Those food packers who pack and ship large quantities of food stuff suchas baby food, have found it advisable in some instances to regularlyreopen cartons .in their warehouses to check the contents of thecontainers for what are termed slow leakers. These are containers inwhich the vacuum seal was satisfactory at the time the container wasfilled and sealed; however, due to the circumstances of handling or dueto the presence of small defects in the lid of the container, the vacuumwas gradually lost during the storage period. Obviously, to reopen andreinspect all of the packed containers, becomes both an expensive andtime-consuming operation.

The present invention provides'a system for inspecting containers havingflip-panel closures for vacuum condi- 3,451,546 Patented June 24, 1969ICC tion without requiring the opening of the cartons in which they arepacked or without requiring removal of the containers from their carton.

Summary of the invention This invention relates to a method andapparatus for inspecting containers having flip-panel closures while thecontainers are closed in a paperboard carton. The containers areinspected for vacuum condition by using a beam of microwave energy whichimpinges on the closure and is reflected therefrom, with the degree ofscattering of the reflected beam being utilized to indicate acceptableor non-acceptable vacuum condition present in the containers. Themicrowaves are produced by a klystron and collimated by a dielectriclens with the collimated output beam is being directed against the metalclosure on the container at a selected angle.

Brief description of the drawings FIG. 1 is a schematic, perspectiveview of the inspection apparatus of the invention;

FIG. 2 is a diagrammatic, side elevational View of the inspection systemof the apparatus when viewing a properly sealed container;

FIG. 3 is a view similar to that of FIG. 2, illustrating the apparatuswhen viewing an improperly sealed container;

FIG. 4 is a schematic circuit diagram of the electronic systemassociated with the apparatus of the invention; and

FIG. 5 is a diagram of the wave forms of the electronic apparatus ofFIG. 4.

With particular reference to FIGS. 1-3, the mechanical details andfunctional operation of the apparatus will be described.

A carton 1'0 which is filled and closed contains a plurality of sealedcontainers 11 having what are termed flip-panel type end closures 12positioned in rows therein. For illustration purposes in FIG. l only thefirst row is shown in which there are depicted four containers. Itshould be readily understood that there are, within the carton 10, aplurality of containers in columns in line with each of the containersin the first row. The carton 10 is moved along a roller type conveyor 13and when the carton is advanced to the position illustrated in FIG. l,the forward edge of the carton will intercept a beam of light whichextends laterally across the conveyor 13 between a source 14 and apickup 15.

Positioned above the conveyor 13 is a klystron 16 of commercial design,it being understood that a klystron is fundamentally an oscillator whichoperates to produce a fairly high frequency output. The output of theklystron is coupled to a T 17 with the base of the T being connected tothe klystron and the two branches of the T being in turn coupled to asecond pair of T couplers 18 and 19. Each of the couplers 18 and 19 hasan output horn 20 and 21 respectively connected thereto. Both the Ts 15and 18 are also coupled to elbow couplings 22 and 23 which in turn havehorns similar to 20 and 21 coupled to their ends. In each instance thehorns are spaced apart the same distance as adjacent containers in a rowwithin the carton 10, with each horn being directed toward an individualcontainer. With this arrangement and with the klystron operating toproduce millimeter waves, the coupled horns will be producing millimeterwave radiation. Each horn has associated therewith and positioned infront thereof, a dielectric lens 24 which serves to collimate themillimeter wave radiation. The collimated millimeter wave coming fromthe dielectric lens 24 passes through an apertured mask 25 which reducesthe size of the collimated millimeter Wave beam to a relatively smallcross-sectional area.

Millimeter waves readily penetrate dielectric material such as cardboardand most plastics with relative, little loss, thus the beam will impingeon the flip-panel portion of the container closures 12 at the centerportion thereof. If the center portion of the container closure 12 isdepressed, or concave in configuration, indicating that a proper vacuumis present within the container, the reected beam of radiation will befocused by the lid.

A metal mask 26 is placed at the focal point of the concave lid so thatthe focused, reflected radiation will be blocked by the mask. This isillustrated specifically in FIG. 2. In the event that the container haslost its vacuum, the nip-panel of the closure will assume a convexconiiguration, as illustrated in FIG. 3. With the convex configuration,the reflected radiation `from the container closure 12 will be divergentor scattered to a certain extent and a substantial portion of theradiation will pass by the metal mask 26. This scattered radiation iscollected by a dielectric lens 27 which will generally focus thereflected radiation into a pickup horn 28. The pickup horns 28, oneassociated with each row of containers, is coupled individually to abolometer 29.

The bolometer is a microwave detector consisting of a piece of line wirewhose resistance changes in proportion to the amount of radiationimpinging on it. The bolometer resistance wire, sensing element isconnected to a bolometer bridge 30 (FIG. 4) which is nothing more thanthree additional resistance wires forming a balanced Wheatstone bridge.The output of the bridge 30 is connected to an amplifier 31 with theoutput of the amplifier being connected to a Schmitt trigger 32.

In the particular embodiment of the apparatus disclosed, there are fourcolumns of containers, thus there are four channels of inspectionpresent with a bolometer associated with each. Thus, for each bolometerthere will be a measuring signal, output channel 34 similar to the onechannel illustrated in FIG. 4 and designated by the dotted lineenclosure and arrow 33. The outputs of the four channels are allconnected to the input of an OR gate 34, it being understood that the ORgate functions to pass a signal when a signal is received Afrom any ofthe input channels 33 or 34.

As previously stated, a light beam extending across the conveyor betweenlight 14 and photo-diode 15 is interrupted when the carton is ininspection position. The photodiode is actually the sensing element of4a light-sensitive Schmitt trigger which is illustrated in block form at36 in FIG. 4. The trigger 36 produces a pulse of limited duration whenthe light is blocked from the photo-diode, with the output signal beingfed to the input of an OR gate 37.

Since there are six rows of containers in the carton, applicant providessix triggering pulses by providing additional light sources 38 andpickups 39, shown connected to triggers 40. Each of the triggers 40` areconnected to the OR gate 37. The OR gate 37 has its output connected toa one-shot or monostable multivibrator 38 whose output is in the form ofa signal having a specific pulse width.

Both the outputs from the one-shot 38 and the "OR gate 35 are connectedto an AND gate 39 with the output of the AND gate connected to a rejectmechanism 40 which may take the form of a motor operated pusher bar formoving a carton having a defectively sealed container therein from theline of the conveyor or may be a signal to indicate to an operator thatthe carton should be selected out.

With particular reference to FIGS. 4 and 5, the 'functional explanationof the gauging circuitry will be given. For simplification, a singlechannel will be described in detail, it being understood that the otherchannels will be functioning in an identical mode.

For an aid in understanding the invention, the waveforms of FIG. 5,designated a-e are applied to the circuit diagram of FIG. 4 at the leadswhich carry the signals of the respective waveforms.

Waveform a of FIG. 5 shows the amplified output of one of the bolometerbridges. The portions of the waveforms designated 41 and 42 representthe periods of inspection when viewing an acceptable container (waveformzone 41) and defectively sealed container (waveform zone 42).

As can be `seen when viewing waveform a, zone 41, the bolometer outputisminimal when the container has a vacuum closure which has retained itsseal. The low output signal is due to the fact that the mask 26 willinterrupt most of the reilected microwaves. The bolometer output,however, will be fairly high when the closure is convex (FIG. 3), andthe signal will appear as at 42 in FIG. 5, waveform a.

The waveform b indicates the signal output of the Schmitt trigger whichtakes the form of a square wave of predetermined amplitude. When theincoming signal to the Schmitttrigger is below a certain level, thetrigger does not lire and, therefore, has no output signal.

Waveform c is the gating signal or read pulse signal due to theinterruption of the cross conveyor beams by the position of the carton.These signals c are applied to a one-shot whose output is of a squarewaveform of predetermined duration corresponding to the period when thecarton and the containers are in inspection position.

When signals are received at both inputs to the AND gate, then a rejectsignal (waveform e) is passed by the AND gate to a reject system.

As can beseen when viewing FIG. 5, when an acceptable container isinspected (zone 41), no signal is passed by the AND gate. When adefectively sealed container is viewed, the square wave b is passed bythe AND gate and the reject system is energized.

As a speciiic example of a mode of operation of the device, the Klystronwas operated to produce radiation of 1.75 mm. wave length. Furthermore,it should be kept in mind that in order to avoid spurious readings, itis necessary that the diameter of the aperture in the mask 25 must be atleast three times the wave length of the radiation passing therethrough.If the mask aperture were too small in relation to the wave length ofthe radiation, then bire-fringence would be produced resulting in la noncollimated radiation beam output.

Other and further modifications may be resorted to without departingfrom the spirit and scope of the appended claims.

I claim:

1. The method of determining when the vacuum in a container enclosed ina paperboard carton falls below a predetermined level which methodcomprises, moving the cartons with the containers therein continuouslyin succession past an inspection station, directing a beam ofelectromagnetic radiation to which the paperboard carton is transparent,directly into the flip-panel of a container 'as it reaches theinspection station, causing said beam to be reiiected by said Hip-panelportion upwardly into a predetermined area, causing a portion of saidreilected beam to bypass said area when the vacuum in the container isunsatisfactory, creating a signal in response to the bypassing of saidreflected beam, directing a second beam of radiant energy in the path ofsaid cartons causing each carton to interrupt said second beam as itreaches the inspection station, creating a pulse of predetermined timeinterval in response to the interruption of said second beam andrejecting the carton when the signal created by the bypassed portion ofsaid iirst beam occurs simultaneously with the time interval of thepulse created 'by interruption of the second beam.

v2. The method of determining when the vacuum in a container enclosed ina paperboard carton falls below a predetermined level where thecontainer includes a liippanel that assumes a concave configuration whenthe vacuum is satisfactory and a convex configuration when the vacuum isunsatisfactory, which method comprises moving the cartons with thecontainers therein continuously in succession past an inspectionstation, directing a first beam of electromagnetic radiation to whichthe paperboard carton is transparent, directly into the flippanel of acontainer as it reaches the inspection station, causing said beam to bereflected by said flip-panel portion upwardly into a predetermined area,causing a portion of said reflected beam to bypass said area when thevacuum in the container is unsatisfactory, creating a first signal inresponse to the bypassing of said first beam, directing a second beam ofradiant energy in the path of said cartons causing each carton tointerrupt said second beam as it reaches the inspection station,creating a pulse of predetermined time interval in response to theinterruption of said second beam and rejecting the carton when the firstsignal created by the bypassed portion of san'd first beam occurssimultaneously with the time interval of the pulse created byinterruption of the second beam.

3. The method of claim 2, further comprising the steps of directing-additional beams of electromagnetic radiation to which the paperboardcarton is transparent, in parallel with said first beam directly intothe flip-panel of the row of containers in the carton, and individuallycreating signals when any of said first beams are reflected divergentlyfrom their respective flip-panels.

4. The method of claim 3, further comprising repeating the steps setforth for each row of containers enclosed within the carton.

5. Apparatus for determining whether the vacuum in a sealed containerenclosed in a paperboard carton is satisfactory, where the container hasa flip-panel that assumes a generally concave configuration when thevacuum in the container is satisfactory and a convex configuration whenthe vacuum in the container is unsatisfactory, the combinationcomprising means for directing a collimated beam of millimeter waveradiation downwardly through the carton onto the flip-panel of thecontainer at such an angle that the beam is reflected from theflip-panel in accordance with the curvature thereof, a mask positionedat the 'focal point of the reflected beam from the flippanel having aconcave configuration, a bolometer, a millimeter wave pickup horncoupled to said bolometer and having its open end in alignment with thereflected beam and said mask, a dielectric collecting lens between thehorn and the mask and adapted to collect millimeter wave radiationpassing beyond the periphery of the mask and direct it into the horn andmeans energized by said bolometer for indicating when the reflectedradiation beam exceeds the size of the mask a predetermined amountindicating that the container has insufficient vacuum.

6. The apparatus of claim 5, wherein said means for directing thecollimated beam yof radiation comprises a millimeter wave klystron, anoutput horn coupled to said klystron and a dielectric lens mounted infront of the output horn for collirnating the millimeter wave radiationfrom the horn.

7. The apparatus of claim 6, wherein said klystron and output horn areoperated to produce radiation of about 1.75 mm. wave length.

8. The apparatus of claim 6, further including an apertured maskpositioned between said dielectric lens and the container closure yforlimiting the size of the incident radiation beam to a size less than thediameter of the flip-panel portion of the closure.

9. The apparatus of claim 8, wherein said klystron and output Ahorn areoperated to produce millimeter wave radiation of a wave length at leastthree times smaller than the aperture in said mask.

References Cited UNITED STATES PATENTS 3,271,668 9/1966 Haake et al.3,379,306 4/1968 Mathias et al 209-1115 ALLEN N. KNOWLES, PrimaryExaminer.

U.S. Cl. X.R.

